1. Field
The present disclosure is related to the field of communications, and more particularly to generating high signal quality across networks and over a wide range of frequencies.
2. Art Background
Communication systems use channels, or physical mediums, to transport signals among multiple points. For example, physical mediums or channels are used to carry signals in networks, including over wide area and local networks. One important design criteria in communication systems is to maintain a high signal quality throughout the network. One aspect of maintaining signal quality is to ensure signals are not degraded as they are propagated through the channels and physical mediums.
The channel may be characterized through its characteristic impedance. For example, some channels may exhibit a characteristic impedance of 50 ohms. The characteristic impedance is measured as both a real (resistive) impedance and an imaginary (reactive) impedance. The reactive impedance is a function of inductance and capacitance on the channel. As such, the reactive impedance component is frequency dependent. Therefore, if a channel transmits signals across a wide range of frequencies, the characteristic impedance of the channel changes across those frequencies.
In network systems, the physical mediums are designed and built to interface with other aspects of the network by matching the characteristic impedance of the channel to the impedances of the channel interfaces. To this end, designers attempt to provide, for signal transmission, a constant characteristic impedance for the physical medium across a range of frequencies. However, it is difficult to provide a constant characteristic impedance across the channel for all frequencies. Mismatches, due to frequency variations, the physical connections, imperfections in the channel, etc., result in imperfect channels that degrade signal quality. A mismatched channel generates signal reflections in the channel that degrade the quality of the signal and cause data dependent jitter, which is a form of inter symbol interference. As such, it is desirable to eliminate or minimize signal reflections on the channel in order to improve the quality of the communications system.
The methods, circuits and systems of the present disclosure provide means for generating high quality signals across physical mediums and interfaces.